1. Field of the Invention
The present invention relates to a nitride semiconductor light emitting device and a method for fabricating the same.
2. Description of the Related Art
Generally, a light emitting diode (LED) is one of the well-known semiconductor light emitting devices. The LED is used to send and receive signal by converting the electric signal into infrared radiation, visible radiation, or light using the characteristic of a compound semiconductor.
The LED is used in various fields such as home electronics, remote controllers, electronic display boards, indicators, automated machines, and so on, and is generally classified into an infrared emitting diode and a visible light emitting diode.
Typically, the downsized LED is made in the type of a surface mount device in order to directly mount it on a printed circuit board. Thus, an LED lamp used as a display device is being developed in the surface mount device type. This surface mount device can replace an existing simple on/off lamp, and is used as an on/off indicator, a character indicator, an image indicator, etc. producing various colors.
As the LED is widely used as described above, the brightness required for an electric light used in everyday life or an emergency signal light is gradually increased. Recently, a high-power LED has been actively developed.
Hereinafter, a related light emitting device will be described with reference to the attached drawings.
FIG. 1 is a sectional view illustrating a related nitride semiconductor light emitting device.
Referring to FIG. 1, the related nitride semiconductor light emitting device has a buffer layer 30, an n-type clad layer 40, an active layer 50, and a p-type clad layer 60, which are sequentially formed on a sapphire (Al2O3) substrate 10.
Then, a p-type electrode 90 is formed on the p-type clad layer 60, and an n-type electrode 80 is formed at one side on the n-type clad layer 40.
When voltage is applied to the n-type electrode 80 and the p-type electrode 90, electrons are injected from the n-type clad layer 40 into the active layer 50, and holes are injected from the p-type clad layer 60 into the active layer 50.
At this time, the electrons and holes injected into the active layer 50 are recombined to produce light having energy corresponding to a band gap difference or an energy level difference.
However, the related nitride semiconductor light emitting device mainly employs sapphire (Al2O3) in order to grow a good quality of nitride semiconductor. The production cost of this sapphire is high, and thus the cost of the light emitting device is increased.
Further, the related sapphire substrate has low electrical and thermal conductivities in itself, and thus results in low heat release. Hence, the light emitting device has a short lifetime, and is difficult to secure its reliability.
Because the related sapphire substrate itself has high insulating property, it can be applied only to a device having a photoelectric characteristic. For this reason, the related sapphire substrate is impossible to fabricate micro-electromechanical system (MEMS) devices and micro optoelectronic integrated circuit (OEIC) devices having the photoelectric characteristic and a combination of electrical and electronic characteristics.